Residential areas and other places are often disturbed by pests, such as gophers and other burrowing animals which cause large amounts of damage to grounds, lawns and gardens. Numerous traps have been designed in the past for eliminating these animals. However, many of these conventional rodent traps have complicated structures in that they are either hard to manufacture or are inconvenient to use. Some of these conventional traps are large and thus the places of their use are limited. Available conventional traps are not 100% effective, thus leaving considerable room for improvement.
A preliminary patentability search was conducted by the applicant which reveals a number of U.S. patents. None of the prior art patents show or suggest applicant's device, especially the features and advantages of the present invention.
U.S. Pat. No. 1,541,985 issued on Jan. 3, 1925 to George A. Marquis discloses an electrocuting rat trap. The trap includes a large circular metallic plate and a small circular metallic plate which is supported on the large metallic plate by a semispherical pivot head and a coil spring. Each of the metallic plates is provided with a contact ring. During use, a bait is placed in a bait holder on the small metallic plate. When a rodent steps on the small metallic plate to remove the bait while the hind legs rest on the lower plate, the two contact rings are thereby brought into engagement with each other. Thus, a circuit using a transformer is turned on to electrocute the rodent. In order to initiate electrocution, the rodent must stand on both the large and the small metallic plates at the same time. This design is inefficient because the rodent may easily disengage from the plates, thereby stopping the electrocution before death, particularly when the front legs of the rodent are withdrawn from the small metallic plate due to the rodent's reaction to the shock.
U.S. Pat. No. 4,048,746 issued on Sep. 20, 1977 to Joseph R. Dye shows an electronic device used to exterminate rodents in their burrows without the removal of soil. The device includes a stick-type carrier for insertion into the soil, a metal sleeve which is installed on the tip of the carrier constituting an electric ground, and two brass rings which are secured on the stick-type carrier serving as touch control and high voltage electrodes. The device further includes a circuit which is connected to the metal sleeve and the two brass rings to test the location of a burrow and provide high voltage current. The circuit includes two control transistors, a relay and a high voltage transformer. The circuit is also provided with a light which gives a continuously visual alarm indicating that a rodent has been electrocuted. This device consumes a good deal of power because the alarm light is illuminated continuously until the user removes the carrier. Further, if the device is not optimally disposed in a burrow, the rodent may not touch the carrier at all. Furthermore, the rodent can easily disengage from the carrier if the rodent is not electrocuted by the first dose of high voltage current.
U.S. Pat. No. 3,468,054 issued on Aug. 15, 1967 to Irving Levine discloses an electrical rodent exterminator. The exterminator includes a casing which has a rodent entrance chamber and metal grids therein. A bait is disposed on the rear wall in the casing. The front of the rodent entrance chamber is open for rodents. There is a swinging baffle hanging vertically in the chamber. If a rodent which comes into the chamber for the bait stands on the grids and pushes the swinging baffle, the swinging baffle will rotate a rod which, in turn, closes the switch in a circuit for electrocuting the rodent. The circuit includes a transformer and a clock timer for providing a timed cycle of high voltage current to the grids. The circuit also has a signal lamp which is turned on after electrocution. Obviously, this type of exterminator has a complicated structure and is not suitable for use in a burrow or other restricted area due to its large size. The exterminator is also power inefficient due to the continual illumination of the signal lamp. In addition, this device is not efficient because electrocution of the rodent requires that the rodent first find the entrance, then move into the chamber, and finally push the swinging baffle in order to trigger the circuit.
Other conventional rodent traps are disclosed in a number of patents including U.S. Pat. No. 4,780,985 issued on Nov. 1, 1988 to Clande G. Coots; U.S. Pat. No. 4,497,130 issued on Feb. 5, 1985 to John P. Fitzgerald; U.S. Pat. No. 4,205,480 issued on Jun. 3, 1980 to William J. Gartner; U.S. Pat. No. 3,827,176 issued on Aug. 6, 1974 to Homer A. Stirewalt; U.S. Pat. No. 4,074,456 issued on Feb. 21, 1978 to Robert Wayne Tedwell; U.S. Pat. No. 3,792,547 issued on Feb. 19, 1974 to Leon E. Day; U.S. Pat. No. 3,197,916 issued on Aug. 3, 1965 to S. L. Cole, Jr., et al; U.S. Pat. No. 3,388,497 issued on Jun. 18, 1968 to I. Levine; U.S. Pat. No. 909,814 issued on Jan. 12, 1909 to Hosea Haxton; U.S. Pat. No. 1,680,594 issued on Aug. 14, 1928 to T. F. Connolly et al; U.S. Pat. No. 2,003,513 issued on Jun. 4, 1935 to L. D. Myers; U.S. Pat. No. 2,098,884 issued on Nov. 9, 1937 to E. B. Rousseau; U.S. Pat. No. 2,161,789 issued on Jun. 13, 1939 to G. L. Wingfield; U.S. Pat. No. 2,191,127 issued on Feb. 20, 1940 to C. T. Hazel; U.S. Pat. No. 2,420,723 issued on May 20, 1947 to H. L. Ratchford; and U.S. Pat. No. 2,595,130 issued on Apr. 29, 1952 to L. R. Edwards. These conventional rodent traps normally include a chamber or channel in which a bait is used to attract the rodent. The rodent has to find the entrance of the chamber before taking the bait. When a mechanical switch in the chamber is touched or moved by the rodent, a circuit is completed to electrocute the rodent. In some of the conventional rodent traps, two elements have to be contacted or pushed at the same time by the rodent in order to trigger the circuit. In addition, these traps are either complicated to manufacture or are inconvenient to use.
Thus, it is an object of the present invention to provide a pest electrocution device which has a simple structure but yet provides high efficiency in dispatching pests such as rodents.
Another object of the present invention is to provide a rodent electrocution device which can be made small in size and without use of a chamber structure so that they can be disposed in rodent burrows or other tight places.
Still another object of the invention is to provide a rodent electrocution device with a trigger mechanism having adjustable sensitivity to actuate the electrocution.
A further object of the present invention is to provide a rodent electrocution device with a mechanism by which the rodent cannot easily break contact once power is applied.
A still further object of the present invention is to provide a status-checking mechanism which allows the user to check the status of the device at any time without interfering with the environment in which the device is located, and without substantially consuming electric power when the status is not checked.
A still further object of the present invention is to provide an output of high voltage but low current spikes which is effective in killing rodents but which is less dangerous to humans.
A still further object of the present invention is to provide a triggered timing circuit which limits the electrocution time to an interval which is effective in killing rodents but which limits the draw on the battery.
These and other objects and advantages of the present invention will become more apparent after studying the following discussion.